GEOPHYSICAL AND UAV-BASED OBSERVATIONS OVER A FLOOD DEFENSE STRUCTURE: APPLICATION TO THE POLDER2C’S EXPERIMENTAL DIKE

We developed a system able to to predict, knowing the appropriate characteristics of the flood defense structure and sea state, the return periods of potentially dangerous events as well as a ranking of parameters by order of uncertainty. The model is a combination of statistical and empirical methods that have been applied to a Mediterranean earthen dike. This shows that the most important characteristics of the dyke are its geometrical features, such as its height and slope angles.

Coastal structures subjected to the actions of waves must be redesigned due to rising sea levels. Their design requires an estimate of the long return period of wave height, wave period, storm surge and more specifically their joint exceedance probabilities. We confirm that the best results are obtained by first aggregating the most correlated variables: wave height and wave period. Nevertheless, the choice of method of aggregation is much less important than the choice of the copula.

This paper deals with the evaluation of the risk associated with coastal flooding by combining the tide with extreme storm surges (SSs). In this work, methods for tide and SS combination were compared. Le Havre in France was used as a case study. Overall, the example has shown that the return level estimates using different combinations are quite different. It has also been suggested that the questions of coincidence and dependency are essential for a combined tide and SS hazard analysis.